AGRICULTURAL CHEMISTRY ^AGROTECHNY. 15 



acid is determined in ttie latter by ignition [with] calcium acetate and finishing 

 in the usual way with ammonium molybdate and magnesium mixture." 



The analysis of maple products. — IV, The composition of maple sugar 

 sand, J. F. Snexl and A. G. Lochhead (Jour. Indus, and Engin. Chcm., 6 

 {191.',), No. Jf, pp. 301, 302). — In this investigation analyses of six samples of 

 washed air-dried Quebec maple sand are reported. " This material contains 

 from G5 to SO per cent of normal calcium malate, from 6 to 18.5 per cent of silica, 

 minor quantities of manganese, magnesium, and phosphorus, traces of iron, and 

 from 10 to 17 per cent of undetermined material." See also a note by Warren 

 (E. S. R., 25. p. 803). 



Determination of benzoic acid in chopped meats, A. Krxjger (Ztschr. Vnter- 

 sueh. Ndhr. u. Genussmtl., 26 {1913), No. 1, pp. 12-20; abs. in Chem. Ztg., 88 

 {191Jf). No. Jflf, Repcrt., p. 203). — The procedure is as follows: 



Dissolve 50 gm. of the chopped meat in a round-bottomed, one-half liter 

 flask with 45 cc. of TO per cent sulphuric acid by heating gently and then dis- 

 till with steam, using precaution that not more 500 cc. is obtained. Then filter 

 the distillate, make slightly alkaline, evaporate to a small bulk in a 100 cc. 

 disk, and treat with a saturated solution of potassium permanganate until a 

 permanent red color remains. Remove the excess of permanganate with 

 sodium .sulphite solution and condense the solution to a bulk of 10 cc. After 

 cooling, place in a cylindrical separatory funnel, acidify, and rinse the evapo- 

 rating dish with sodium sulphite solution and sulphuric acid. Then shake the 

 benzoic acid solution, which should amount to from 15 to 20 cc, several times with 

 ether-petroleum ether, wash the combined ethereal solution several times with 

 3 cc. of water, and shake with a little (as much as will go on the tip of a 

 knife) powdered gum tragacanth. Allow the etheral solution to evaporate 

 spontaneously in a weighed dish, dry the residue over soda lime, and weigh. 

 As a control the residue is dissolved in a little neutralized alcohol and titrated, 

 or any benzoic acid still pi'esent may be isolated by sublimation in the Polenske 

 apparatus (E. S. R., 27, p. 715). 



A shorter method consists in shaking out the benzoic acid fi'om the steam 

 distillate with several portions of benzol containing equivalent amounts of 

 soda solution. The extracts must also be treated with potassium permanganate 

 to remove the fatty acids. 



A note on the quantity of benzoic acid contained in prunes and cranber- 

 ries, M. J, Radin {Jour. Indus, and Engin. Chem., 6 (1914), No. 6, p. 518). — 

 For the estimation of benzoic acid Kriiger's method was employed with a 

 charge of 50 gm. of fruit. From several duplicate analyses in each instance 

 it was found that prunes, as obtained in the market, contained approximately 

 0.05 per cent benzoic acid and cranberries 0.06 per cent. 



" These results were furnished from the weight of sublimed benzoic acid and 

 by titration, the data in each instance agreeing closely." 



Determination of Prussian blue in tea, G. W. Knight (Jour. Indus, and 

 Engin. Chem., G (1914), No. ii< PP- 909, 910). — ^The method consists of decom- 

 posing the Prussian blue in the tea with 85 per cent phosphoric acid and 

 collecting the hydrocyanic acid in a 10 per cent sodium hydroxid solution. The 

 hydrocyanic acid is then reconverted into Prussian blue and weighed as 

 such. " By means of it one part in 200,000, and sometimes even one part in 

 300,000, can be detected. A man inexperienced in the manipulation can run 

 four determinations in a day easily, and doubtless with experience could rim 

 many more. Two operators working independently on the same sample 

 obtained 0.0019 and 0.0016 per cent of Prussian blue." 



Several samples of uncolored China and Japan teas were examined by the 

 method, but no Prussian blue was found. 



